Galactoside-binding lectin. Animal lectins display a wide variety of architectures. They are classified according to the carbohydrate-recognition domain (CRD) of which there are two main types, S-type and C-type. Galectins (previously S-lectins) bind exclusively beta-galactosides like lactose. They do not require metal ions for activity. Galectins are found predominantly, but not exclusively in mammals. Their function is unclear. They are developmentally regulated and may be involved in differentiation, cellular regulation and tissue construction.

Galectin/galactose-binding lectin. This domain exclusively binds beta-galactosides, such as lactose, and does not require metal ions for activity. GLECT domains occur as homodimers or tandemly repeated domains. They are developmentally regulated and may be involved in differentiation, cell-cell interaction and cellular regulation.

Galactosyltransferase. This family includes the galactosyltransferases UDP-galactose:2-acetamido-2-deoxy-D-glucose3beta-galactosyltransferase and UDP-Gal:beta-GlcNAc beta 1,3-galactosyltranferase. Specific galactosyltransferases transfer galactose to GlcNAc terminal chains in the synthesis of the lacto-series oligosaccharides types 1 and 2.

Interacting selectively and non-covalently with any carbohydrate, which includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction of the carbonyl group (alditols), by oxidation of one or more hydroxy groups to afford the corresponding aldehydes, ketones, or carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom. Cyclitols are generally not regarded as carbohydrates." [CHEBI:16646, GOC:mah]